text: /* Copyright (C) 2007-2010 Open Information Security Foundation
   *
   * You can copy, redistribute or modify this Program under the terms of
   * the GNU General Public License version 2 as published by the Free
   * Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * version 2 along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   * 02110-1301, USA.
   */
  
  /**
   * \file decode-gre.h
   *
   * \author Breno Silva <breno.silva@gmail.com>
   *
   * Generic Route Encapsulation (GRE) from RFC 1701.
   */
  
  #ifndef __DECODE_GRE_H__
  #define __DECODE_GRE_H__
  
  #ifndef IPPROTO_GRE
  #define IPPROTO_GRE 47
  #endif
  
  #include "decode.h"
  #include "threadvars.h"
  
  typedef struct GREHdr_
  {
      uint8_t flags; /**< GRE packet flags */
      uint8_t version; /**< GRE version */
      uint16_t ether_type; /**< ether type of the encapsulated traffic */
  
  } __attribute__((__packed__)) GREHdr;
  
  /* Generic Routing Encapsulation Source Route Entries (SREs).
   * The header is followed by a variable amount of Routing Information.
   */
  typedef struct GRESreHdr_
  {
      uint16_t af; /**< Address family */
      uint8_t sre_offset;
      uint8_t sre_length;
  } __attribute__((__packed__)) GRESreHdr;
  
  #define GRE_VERSION_0           0x0000
  #define GRE_VERSION_1           0x0001
  
  #define GRE_HDR_LEN             4
  #define GRE_CHKSUM_LEN          2
  #define GRE_OFFSET_LEN          2
  #define GRE_KEY_LEN             4
  #define GRE_SEQ_LEN             4
  #define GRE_SRE_HDR_LEN         4
  #define GRE_PROTO_PPP           0x880b
  
  #define GRE_FLAG_ISSET_CHKSUM(r)    (r->flags & 0x80)
  #define GRE_FLAG_ISSET_ROUTE(r)     (r->flags & 0x40)
  #define GRE_FLAG_ISSET_KY(r)        (r->flags & 0x20)
  #define GRE_FLAG_ISSET_SQ(r)        (r->flags & 0x10)
  #define GRE_FLAG_ISSET_SSR(r)       (r->flags & 0x08)
  #define GRE_FLAG_ISSET_RECUR(r)     (r->flags & 0x07)
  #define GRE_GET_VERSION(r)   (r->version & 0x07)
  #define GRE_GET_FLAGS(r)     (r->version & 0xF8)
  #define GRE_GET_PROTO(r)     SCNtohs(r->ether_type)
  
  #define GREV1_HDR_LEN           8
  #define GREV1_ACK_LEN           4
  #define GREV1_FLAG_ISSET_FLAGS(r)  (r->version & 0x78)
  #define GREV1_FLAG_ISSET_ACK(r)    (r->version & 0x80)
  
  void DecodeGRERegisterTests(void);
  
  #endif /* __DECODE_GRE_H__ */
  
  